Capitalizing on spying tools believed to have been developed by the U.S. National Security Agency, the cyber assault launched on Friday has infected tens of thousands of computers in 104 countries, with Britain's health system suffering the worst known disruptions.

A MASSIVE cyber attack has targeted NHS < National Health Service> sites across the country with ransomware, plunging them into chaos....Some 48 hospitals are understood to have been affected...37 hospitals the NHS has revealed have been attacked directly and those that shut down their systems as a precaution...